1. Field of the Invention
The present invention relates to novel perovskite catalysts, methods for their preparation and uses thereof in hydrocarbon conversion processes.
2. Description of the Prior Art
It is known that perovskites can be used as hydrocarbon conversion catalysts (see, for example, U.S. Pat. Nos. 3,595,809; 3,450,789; 3,780,126; and U.K. Pat. No. 1,352,995). The conventional method of preparing pure perovskites has been a repetition of the steps of high temperature fusion of a mixture of metal oxides and ball milling to reduce the fused mass to submicron size particles and to expose fresh unreacted oxide for the repeated fusion step. Due to the repeated high temperature treatments which induce melting and sintering, the thus prepared perovskites have relatively low surface areas, typically from about 1 to about 20 m.sup.2 /g (BET).
U.S. Pat. No. 3,897,367 discloses perovskite-type compounds which may be employed as catalyst in the form of coatings on suitable refractory supports.
For use as catalysts, especially for use as hydrocarbon conversion catalysts, it is desirable to obtain high surface area perovskites. Attempts to produce supported high surface area perovskite catalysts by simple impregnation techniques on alumina gel resulted in a supported spinel and not in the desired supported perovskite.
It has now been found that high surface area perovskite catalysts can be produced by the preparation methods of the present invention.